Problem: A rectangle is $1$ centimeter long. The rectangle is also $8$ centimeters wide. What is its perimeter?
Solution: $1\text{ cm}$ $8\text{ cm}$ The perimeter is the total length of all the sides of the shape added together. Add up the lengths of the sides: $ \text{perimeter} = {8} + {1} + {8} + {1} $ $ \text{perimeter} = 18\text{ cm} $